A touch input device indicates an input device that senses the contact position of a finger or the like on a touch panel and provides information on the sensed contact position as input information. The touch panel of the touch input device may be installed to overlap with a display screen or provided separately from therefrom, and information on whether there is a contact and information on contact position may be used for the operation control and screen manipulation of a computer system on which the touch input device has been loaded. There are various types of touch input devices—the representative types being resistive and capacitive types. The capacitive type is largely a self-storage mode and a mutual storage mode.
The mutual storage mode has an operating electrode and a sensing electrode that are made of a transparent conductive material, and a capacitance may be formed between the two electrodes. Usually, directions in which the operating electrode and the sensing electrode are extended are different from each other and in some embodiments, the two electrodes may be perpendicular to each other. The capacitance may be formed between the sensing electrode and the operating electrode and especially, most capacitance may be formed at the intersection region of the two electrodes. Such an intersection region may be collectively referred to as a ‘touch node’ or ‘node’ in the present disclosure. Since a single touch panel provides one or more operating electrodes and one or more sensing electrodes, there may be one or more touch nodes that have been described above.
When a finger approaches or makes contacts with the touch node, the value of the capacitance at the touch node varies. Thus, when measuring a variation in the capacitance value at the touch node, it is possible to find whether the finger has made contact with the touch panel.
To this end, when applying an operating signal to the operating electrode, a charge is injected into the sensing electrode. Since an amount of injected charge varies according to the value of the capacitance between the two electrodes, it is possible to find a variation in capacitance by measuring the amount of the injected charge and thus it is possible to find whether a touch input has been performed.
Many operating electrodes and many sensing electrodes may be disposed on the touch panel and these electrodes are connected to operating circuits and sensing circuits, respectively. For the connection, operating lines and sensing lines are connected to the operating electrodes and the sensing electrodes. Each operating line and sensing line may be designed so that they are electrically isolated from each other. When the operating electrode and the sensing electrode are disposed on the same layer, various structures may be presented in order to insulate the operating lines and the sensing lines from each other. In the present disclosure, the operating line and the sensing line may be collectively referred to as lines.
The detailed operating principle of the touch panel having the mutual storage mode is disclosed in Korean Patent Laid-Open No. 10-2013-0109919, published on Oct. 8, 2013, in which FIGS. 2a to 2C, and 3a describe that an amount of variation of the capacitance at the touch node according to a variation in touch input coordinate fails to maintain linearity about a variation in the touch input coordinate. Such non-linearity works as a limitation in calculating an accurate touch input position. Also, FIG. 4a in Korean Patent Laid-Open No. 10-2013-0109919 shows a particular example related to the disposition of the sensing electrodes, the operating electrodes, and the lines, in which a region occupied by the lines may be referred to as a ‘dead zone’. The density of the lines disposed in such a dead zone varies according to the position of the dead zone and thus there is a limitation in that the above-described linearity required for the detection of the accurate touch input position worsens due to such non-uniformity of patterns.
The concept of the ‘touch node’ described in the present disclosure is disclosed in Korean Patent Laid-Open No. 10-2013-0109919, the entire contents of which are hereby incorporated by reference.